The most visible enhancement to this new firmware is the addition of Proxy Mode on top of the existing Universal Mode and WDS Mode of operation.

The Proxy Mode is said to have the best compatibility with routers and access points of all brands. If your range extender has problem working in Universal Mode and WDS Mode, you can try using this Proxy Mode. However, it may decrease the overall performance.

Note that you might lost all your existing settings in the TL-WA860RE after the firmware upgrade. Anyhow, there are not much settings for the device, so you can redo all the settings without taking up much of your time and effort.